Quantitative phase microscopy for cellular dynamics based on transport of intensity equation

Area of Science:

• Biophysics
• Optical Imaging
• Cell Biology

Background:

• Quantitative phase imaging (QPI) is crucial for label-free, non-invasive analysis of transparent biological specimens.
• Existing QPI methods can be complex, expensive, or require specialized equipment, limiting their widespread application.
• The transport of intensity equation (TIE) offers a promising framework for phase retrieval from intensity images.

Purpose of the Study:

• To develop and validate a simple, cost-effective method for quantitative phase imaging of transparent objects.
• To demonstrate the applicability of the method for dynamic, label-free imaging of living cells.
• To confirm the method's accuracy using well-characterized samples.

Main Methods:

• Utilized an inverted bright-field microscope equipped with a novel, lens-free flipping imaging module.
• Acquired two laterally separated, unequally defocused images simultaneously.
• Reconstructed quantitative phase images using the transport of intensity equation (TIE).

Main Results:

• Successfully performed quantitative phase imaging of a microlens array, validating the system's accuracy.
• Demonstrated dynamic, quantitative phase imaging of human osteoblastic cells in culture.
• The developed add-on module proved to be cost-effective and easy to align.

Conclusions:

• The proposed TIE-based method provides a simple, non-invasive, and label-free approach for quantitative phase imaging.
• The technique is suitable for dynamic measurements of living cells and other transparent specimens.
• This cost-effective solution has significant potential for biological and materials science applications.